<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<input type="file" id="upload"/>
<button onclick="start()">分片</button>
<script>
    function start() {
        const file = document.getElementById("upload");
        console.log(file)
    }


</script>
</body>
</html>